1. Field of the Invention
The present invention relates to personal telephone systems that are able to transmit and receive digital signals between fixed sets and fixed stations in a cordless system. More particularly, the present invention relates to providing a hierarchical call control with a selective broadcast messaging service in a cordless telephone system.
2. Description of the Related Art
Time division multiple access (TDMA) cordless phone systems provide a base unit which is able to provide connections for a plurality of mobile units, such as handsets. Such TDMA systems use time division to provide a plurality of slots, where the base (fixed part (FP)) transmits to an individual (portable unit (PP)) mobile unit during a particular slot of time and receives from the individual mobile unit during a particular slot of time. One standard for TDMA systems is the Digital European Cordless Telecommunications DECT Common interface standard described in ETS 300 175-2 and ETS 300 175-3, published by the European Telecommunication Standards Institute. The DECT standard is also discussed in U.S. Pat. No. 6,078,574 entitled “PROCESS AND APPARATUS FOR ACTION CONTROL IN A TIME SLOT METHOD”, to Boetzel et al. issued Jun. 20, 2000 and U.S. Pat. No. 6,088,338 entitled “METHOD AND SYSTEM FOR THE DETERMINATION OF THE PSCN PARAMETER STARTING FROM THE MFN PARAMETER IN A DECT CORDLESS TELEPHONE SYSTEM” to Rossella et al. issued Jul. 11, 2000, which are incorporated by reference Generally, the DECT standard does not provide a specification to send a voice message to all mobile units simultaneously as a broadcast.
This unfortunate lack of a capability to simultaneously send a voice message to all mobile units associated with a base unit as a broadcast precludes providing a real time hierarchical call control system in a cordless system. For example, most people do not want to be disturbed by telemarketers, poll takers, solicitors, and other telephone calls of such a commercial nature. In addition to unwanted commercial calls, there are times when a consumer would like to be able to identify an unwanted caller (be it personal or business) and not pick up the phone.
Unfortunately, since conventional cordless telephone systems do not provide a broadcast mode, it is impossible for a base station to send a call from an identified caller to only a specific mobile unit. Conventional cordless systems are also incapable of broadcasting a message that is deemed to be an important message to all, or even a selected group, of mobile units.
Therefore, in a cordless phone system having a base station and a plurality of mobile units, it is desirable to provide a mechanism whereby an identified call is sent only to a specified mobile unit whereas an important call is broadcast to most of the mobile units and a mechanism whereby a broadcast message is delivered to only selected mobile units.